#! /bin/bash
#
# A simple shell script for secure and relative fast delete; a replacement for rm,
# similar to srm (see "secure rm" on sourceforge.net).
# Because of saveral bugs and not implemented features, srm and this script can't 
# be used to replace rm.
# This script overrites the file(s) with random bytes, sets the file length to
# zero, renames it and then deletes the empty file.
# The bottleneck is /dev/urandom with a speed of about 3 MByte/s.
# It does not make sense to execute this script in another partition.
#
# Successfully tested with undelete tools like Undelete PLUS.
#
# TODO: Version which works with special signs like newline in the file
# name and which converts the file names with their absolute path
# because otherwise find can read them as options if they have the same name.
#
# License: GPL
#
# rolf dot freitag at email.de 2000, 2007

# Version 2.2, 2010

# for debugging
#set -x

# Return a random filename (including the path) by appending a random number 
# and recurse in case of a collision. So this script should only run in the same partition.
function gettmpfilename()
{
  #local tmpfile="$1"$RANDOM
  #tmpfile="$1"$RANDOM
  tmpfile=$RANDOM
  if [ -e "$tmpfile" ]
  then
    # if file already exists, recurse and try again
    tmpfile=$(gettmpfilename "$1")
  fi
}


# main
for file in "$@"
do
  # make the file writable for the user
  # chmod u+w "$file"
  typeset -i size=`find "$file" -printf "%s"` || continue
  # overrite all $size > 0 bytes of the file
  if [ $size -gt 0 ]
  then
    ddrescue --max-size=$size /dev/urandom "$file"
    # for a version without ddrescue:
    #dd bs=1 count=$size if=/dev/urandom of="$file"
    # flush all buffers via sync !!!
    sync
  fi
  # set size to 0; see also "Unix Power Tools"
  > "$file"
  # flush all buffers via sync !!!
  sync
  # rename
  gettmpfilename "$file"
  mv "$file" "$tmpfile"
  # flush all buffers via sync !!!
  sync
  unlink "$tmpfile"
  # flush all buffers via sync !!!
  sync
done
  
exit 0